Pain Panel Supports Expanding Use of Implanted Drug Delivery: Need for Patient Evaluation Is Stressed

A panel of pain management specialists recently released consensus guidelines intended to help clinicians identify patients experiencing cancer-related pain who would benefit from receiving medication through implanted intrathecal (IT) drug delivery systems, and endorsed “a much wider application” of such therapies.

The group consisted of 10 clinicians from university and pain specialty facilities in the United States and 1 from Australia whose findings were published in the May/ June issue of Pain Physician.

The authors said randomized trials and observational studies have shown that IT systems are viable treatment options that can deliver improved pain relief when compared with conventional therapies, but that patients should be carefully evaluated to determine whether they are candidates for such systems.

IT systems involve positioning a catheter in the cerebral spinal fluid, necessitating the surgical placement of a pump for long-term therapy.

“With careful consideration of the patient’s medical comorbidities and prior therapies, communication with the oncologist, proper psychological evaluation, and appropriate trialing technique, clinicians can effectively optimize the use of IT therapy for cancer pain,” the paper said.

Regarding the prevalence, impact, and need for better treatment for cancer-related pain, the authors reported:

• The prevalence of pain in patients with early cancer disease may be as high as 30% to 40%, and as high as 70% to 90% in patients with advanced disease.
• Nearly two-thirds of patients with advanced incurable cancer may suffer from pain, and one-third of these patients may suffer severe pain.
• Noncancer pain is “highly prevalent and increasing” in patients who also suffer from cancer-related pain.
• Nearly two-thirds of patients may experience breakthrough cancer pain.

Adverse effects associated with IT drug therapy include opioid-induced hyperalgesia, hypotension, sedation, respiratory depression, inflammatory mass, hypogonadotropic hypogonadism, and immunologic compromise.

Other dangers associated with this approach to pain management include increased mortality risk from rapid and improperly monitored dose escalation. To guard against adverse events, the panel recommended that “therapy be initiated at low doses, with slow titration upward, as necessary, based on patient response.”

Recommendations for selecting patients for treatment with IT drug therapy include:

• Clinicians should consider the intensity of the patient’s pain and use “objective and subjective quality-of-life measures” when initiating and titrating therapy.
• Patients with intractable cancer-related pain should be treated with a stepped approach, “beginning with the most conservative therapeutic options and progressing to more aggressive regimens when analgesia is inadequate or adverse effects are intolerable.”
• There is no reliable evidence confirming “a direct association between a patient’s response to oral opioids and ensuing response to IT therapy.”
• In patients undergoing chemotherapy, a white blood cell count ≤2 x 109/L and/or an absolute neutrophil count ≤1000/μL may constitute a contraindication for implantation of an IT device; patients with a white blood cell count ≤1.5 x 109/L can be considered for the procedure “provided they are receiving growth factor treatment.”
• Although IT therapy ‘is a useful strategy for immunocompromised patients,” the panel recommends “mitigation of infection reduction during trialing and implantation” and careful titration and medication selection.
• Patients who display systemic signs of infection should not receive IT drug therapy.
• When using anticoagulant and antiplatelet agents, clinicians should follow the American Society of Regional Anesthesia and Pain Medicine guidelines.

Because it “may be difficult to overstate” the role that psychological factors and emotional stresses play in patients’ response to pain and pain treatment, clinicians should consider conducting a preimplantation psychological evaluation based on the status of the patient’s disease. The authors identified 3 levels of need:

• Patients whose “life expectancy is significantly compromised” and for whom therapy is primarily designed for palliation—Pretrial/ internalization psychological evaluation is optional.
• Patients whose disease process “has been arrested, but wherein there is a significant probability of recurrence”—Psychological evaluation is encouraged, “with an emphasis on periodic psychological consultation/intervention to assist with changes in disease process/ recurrence and coping.”
• Patients whose tumors have been destroyed but are suffering residual chronic pain secondary to treatment—Psychological evaluation is recommended, “in much the same way as those with chronic noncancer pain.”

Although IT drug therapy trials prior to permanent device implantation can be used to “determine patient response to therapy and establish a baseline measurement from which potential improvement can be assessed,” research has not yet established “a direct correlation between a patient’s response during an IT trial and subsequent effects of therapy.”

Thus, the panel reminds that “it is up to the implanting clinician to weigh the benefi ts and limitations of each trialing method and decide which technique—if any—is best suited for the patient.” The panel also recommends against the use of mandatory IT drug trials, especially for patients near the end of life.

Deer TR, Smith HS, Burton AW, et al. Comprehensive consensus based guidelines on intrathecal drug delivery systems in the treatment of pain caused by cancer pain. Pain Physician. 2011;14(3):E283-E312. http://tiny.cc/o7wrf